activity_maps.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="match_parent"
    android:layout_width="match_parent">
    <android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/mainCoordinatorLayout"
        android:layout_width="match_parent"
        android:layout_height="550dp"
        android:fitsSystemWindows="true"
        tools:context=".MapsActivity">

        <fragment xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:tools="http://schemas.android.com/tools"
            android:id="@+id/map"
            android:name="com.google.android.gms.maps.SupportMapFragment"
            android:layout_width="match_parent"
            android:layout_height="550dp"
            tools:context="com.example.chan24.smartplanner.MapsActivity" />


    </android.support.design.widget.CoordinatorLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentEnd="true"
        android:layout_marginEnd="11dp">

        <Button
            android:id="@+id/shopping"
            android:layout_gravity="bottom"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="Shopping"
            android:layout_alignParentBottom="true"
            android:layout_alignEnd="@+id/supermarket"
            android:layout_weight="1"
            android:background="#0000FF"
            />

        <Button
            android:id="@+id/dining"
            android:layout_gravity="bottom"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="Dining"
            android:layout_alignParentBottom="true"
            android:layout_toEndOf="@+id/shopping"
            android:layout_marginStart="46dp"
            android:background="#FFA500"
            android:layout_weight="1" />

        <Button
            android:id="@+id/supermarket"
            android:layout_gravity="bottom"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="Supermarket"
            android:layout_alignParentBottom="true"
            android:layout_alignParentEnd="true"
            android:layout_weight="1"
            android:background="#7FFF00"/>

    </LinearLayout>

</RelativeLayout>